All about the muscles

The space between a motor neuron and muscle fiber

Neuromuscular junction

A chemical messenger that transmits messages between neurons or from neurons to muscles

Neurotransmitter

The neurotransmitter (unique to the motor neuron) released by an action potential at the neuromuscular junction

Acetylcholine

The interaction of actin and myosin that describes the process of muscle contraction

Sliding-filament theory

Slow-twitch fibers and aerobic

Type I

Fast-twitch and anaerobic (good for power)

Type II

Fast-twitch, moderately fatigable muscle fibers with moderate mitochondrial density

Type IIa fibers

Fast-twitch, fast-fatigable muscle fibers with low mitochondrial density (white in color)

Type IIx fibers

An organelle with a double membrane and many folds inside are responsible for generating the chemical energy needed for biochemical reactions; the “powerhouse of the cell”

Mitochondria (singular “mitochondrion”)

Muscles that shorten to produce movement. For example, during the pressing motion of a bench press, the pectoralis is concentrically contracting.

Concentric

Muscles that lengthen to allow movement. For example, during the downward motion of a biceps curl, the biceps brachii is eccentrically contracting. When applying tempo training, this is the part of the movement that should be the focus and, therefore, the slowest portion of the repetition.

Eccentric

Muscles where the joint angle and muscle length do not change during movement. For example, the entire body works to maintain a stable position when performing a plan

Isometric